Mercury tube switch



March 6, 1934. K H N IKER 1,950,178

MERCURY TUBE SWITCH Filed Jan. 18, 1952 INVENTOR KARL HUNCIKER BY a z: M TTORNEY Patented Mar. 6, 1934 PATENT OFFICE MERCURY TUBE SWITCH Karl Hunciker, Chicago, Ill., assignor to Ira E. McCabe, Chicago, Ill.

Application January 18, 1932, Serial No. 587,267

4 Claims.

This invention relates to improvements in electric switches and more particularly to mercury tube switches in which a small quantity of mercury is sealed in a glass tube and caused to move into and out of contact between two electrodes passing through and sealed in the walls of the tube to close and open the circuit between the said electrodes.

This invention is a further development of the applicants switch illustrated and described-in his prior application Serial No. 554,182, filed July 31, 1931, which became Patent No. 1,882,614 on Oct. 11, 1932 in which the mercury tube was held at an angle and was provided with means pivoted within the tube adapted to be actuated by external magnetic means to bodily move the small portions of mercury to contact the electrodes to close the circuit through the switch. In the said patent the mercury was propelled or caused to travel over a portion of the tube and it re- .quired precision in assembling the parts so that the propelling or moving members traveled sufficiently close to the tube, without binding, to move the mercury.

The present invention contemplates carrying the small body of mercury upon the pivoted mov-' able means actuated by the external magnetic force to close the circuit thereby providing a cradle for the mercury which swings clear of the walls of the tube and can be assembled with less precision, thus eliminating friction between the mercury and glass tube so that should, after long use, the mercury deteriorate so as to become sticky there is no increase in friction and the switch will operate throughout its life uniformly with a constant application of magnetic force.

With these and other objects in View reference is made to the accompanying sheet of drawings whichfillustrate a preferred embodiment of this invention with the understanding that minor detail changes may be made without departing from the scope thereof.

In the drawing:

Figure 1 is a view in vertical central section with the. electrodes, leading in wires and swinging cradle shown in full line, illustrating the normal positions of the switch tube and parts when the circuit is broken therethrough.

Figure 2 is a similar view, illustrating the position assumed by the parts when the circuit is closed therethrough.

Figure 3 is an enlarged detail view in section taken on the line'33 Figure 5 of the mercury cradle.

Figure 4 is an enlarged detail view in side elevation of the electrodes and swinging cradle before assembly in the tube.

Figure 5 is a view in front elevation of Figure 4.

Figure 6 is a View similar to Figure 1 showing the manner the mercury is caused to enter the cradle.

Figure 7 is an enlarged fragmentary view of modified form of scoop, shown in section.

In the embodiment of this invention illustrated leading in wires 1 and 2 are sealed in the closure 3 of the glass tube 4, preferably on each side of the sealed off filling stem 5, all of which is a commercial form of mercury tube switch construction as well as welding electrodes 6 and '7 to the leading in wires 1 and 2. The electrodes 6 and '7 terminate adjacent each other at the same side of the axis of the tube and also adjacent the side thereof, as shown in Figures 1 and 5, and the free end of each electrode is bent at right angles toward the axis of the tube or, as shown, are provided with a right angular projection welded thereto, it being preferable to have one projection 8 extending nearer the said axis than the other projection 9. It therefore becomes necessary to bend this electrode 6 within the tube as shown.

A relatively small body or globule of mercury U 10 is carried in a cradle pivotally mounted upon the electrode '7. This oracle is preferably struck out of a blank of magnetic metal and thereafter bent to form at one end semi-circular bearing ears 11; a curved actuating surface 12 of considerable extent; and legs 13 depending from opposite corners of the actuating surface joining a curved mercury scoop 14, the lower edge of which is split and bent to form the bottom 15 to carry the mercury 10; The electrode '7 is oifset within the tube and mounts a pivot 16 which is engaged by the bearings of the ears 11, so that the cradle may swing thereon, which pivot may be welded to the electrode or may be insulated therefrom, if desired. The legs 13 are shaped to carry the mercury 10 opposite the ends 8 and 9 of the electrodes and the cradle is oscillated about its pivot to receive said ends therein. The scoop is provided with a flared top portion 1'7 adapted in one position to contact throughout the side of the tube 4, to provide a track to be followed by the globule of mercury 10 to enter the cradle when it is desired to secure the switch in position for operation.

While it is preferable to employ a fixed magnet 18 to operate the switch any desired type of magnet may be used. The globule of mercury 10 is but a small quantity of mercury and will roll freely about the tube 4- during transportation. When it is desired to install the switch it is first inverted and then the scoop end is depressed and as the mercury 10 descends it will travel over the flared tip 17, enter the scoop 14 and rest upon the bottom 15, thereafter the tube is secured in the position shown in Figures 1 and 2. As shown in Figure 1, the weight of the scoop 14 carrying the mercury 10 maintains the tip 17 in contact with'the wall of the tube 4' opposite the ends 8 and 9 of the electrodes. The magnet 18 is mounted in any desired manner to approach and recede from the tube adjacent the actuating surface 12 of the cradle, so that whenthis surface enters the magnetic field, it will cause the cradle to swing about its pivot 16 until the said surface engages the wall of the tube 4, as shown in Figure 2, thereby carrying the mercury 10 into contact first with end 8 and thereafter with end 9 of the two electrodes to close the circuit therethrough and as the magnet 18 is withdrawn the cradle will return by gravity to the position shown in Figure 1 to break the circuit through the switch.

The electrodes 6 and ,7 are shaped as shown, the leading in wires 1 and 2 welded thereto and the cradle is mounted upon the pivot 16, so that the leading in wires may be held in a workholder while the open end of the tube 4 is passed thereover, heated and the seal 3 formed by any desired commercial machine now in use.

From the above it is seen that while the mercury may travelabout the interior of the tube, it is readily caused. to travel with its operative positions in the cradle, the cradle carries the mercury into and out of. contact with the elec- (trodes while the mercury is supported free from the walls of the tube, whereby the circuit may be made and broken uniformly upon the application of a constant magnetic force to the actuating.

surfaces of the cradle throughout the life of the tube.

As heretofore stated, the pivot 16 of the carriage may either be welded to the electrode '7 or may be insulated therefrom because it is not desired to construct the cradle to act as one of the electrodes of the switch for such construction would result in the sticking of the bearing pivots because of arcing at those points, and for this reason when welding it is preferable that the projection 8 extending from electrode 7 be of such length as to be engaged by the mercury in closing the circuit before the projection 9 from the electrode 6 be engaged thereby.

It has been found that by forming the bottom 15 of the cradle in the form of a cup 15*, as shown in Figure 7, so shaped as to hold only the correct amount of mercury required for the operation of the switch then such mercury within the tube which is in excess of that amount will overfiowto the bottom of the tube and be free from contact with any of the switch parts. This arrangement eliminates exactness in production in providing at all times the correct amount of mercury for the current capacity of the switch and insures that the actuating parts of all switches thus made will respond in a like manner when actuated by the magnet.

What I claim is:

1. In a sealed liquid contact switch having electrodes sealed in the walls thereof and a small quantity of conducting liquid, the provision of a cradle mounted to swing within the container having a portion adapted to carry the said liquid out of contact with said electrodes and a portion of magnetic metal adapted upon the application of an external magnetic force to swing the cradle to bodily bring the liquid into contact with the electrodes to close the circuit through the switch.

2. In a sealed liquid contact switch, electrodes sealed in the walls and terminating adjacent each other, a cradle pivotally mounted upon one electrode to swing free of the other electrode, and a quantity of conducting fluid carried in the cradle independentof and out of contact with the walls of the container and the said electrodes, said cradle having a portion of magnetic metal adapted to cooperate with an external magnet to swing the cradle to cause the liquid to bridge the electrodes to close the circuit. i

3. Ina sealed liquid contact switch, electrodes sealed in the walls and terminating adjacent each other, a cradle mounted upon a pivot carried on one electrode to swing 'free of the other electrode terminating in a scoop having a closed lower end with a flared projection thereabove adapted to engage the walls of the container, and a body of conducting fluid adapted 'to be caused to flow over the flared top into the scoop and be supported therein independent of and out of contact with the walls of the container and the said electrodes, separated from and in line with the ter-' minations of both electrodes, said cradle having a portion of magnetic metal interposed between the pivot and scoop adapted to coact with an .external magnet to swing the cradle to bring the conducting fluid into contact with the electrodes to close the circuit through the switch. I

i. In a sealed liquid contact switch having electrodes sealed in the walls thereof and a small quantity of conducting liquid, the provision of a cradle mounted to swing within the container having a portion adapted to carry the said liquid out of contact with the walls of the switch and said electrodes and a portion of magnetic metal adapted upon the application of an external magnetic force to swing the cradle to bring the liquid \3(- into contact with the electrodes to close the circuit through the switch, said cradle portion a apted to carry said contacting fluid being in th form of a cup in which all fluid in excess of that required overflows therefrom. .35

KARL HUNCIKER. 

